(a) Field of the Invention
The present invention relates to dynamic speed finding method, and more particularly to one that finds the position and speed of a moving police vehicle using signals transmitted from GPS, the relative position and relative speed of a speeding car found with a range and speed finder mounted in the police vehicle to calculate a speed of the speeding car to enforce a ban on the vehicle driving against traffic regulations according to the calculated speed.
(b) Description of the Prior Art
To maintain driving safety and improve traffic condition, traffic control authorities will set speed limits at various spots depending on traffic flow and usually test finding units are erected to ban speeding by taking photos. Radar speed finders generally available in the market include USA specification, European specification and stationary photography system.
Usually radar has a wide angle of transmission that can't lock up a specific car in case of heavy traffic and it may easily attract disputes, while a laser system has a small angle of transmission to lock up a specific car. For the radar or laser speed finder, it must remain still while taking a photo of a speeding car and the included angle between the speeding car and the speed finder must be small enough to get correct speed value disregarding the speed finder is of stationary or hand-held type. There is a different type of a speed finder, such as the Autovelox 104/c2 made in Italy, that it finds the car speed by emitting two parallel beams of light, then included angle between the speeding car and the speed finder must be near 90°. Response time is another factor to be considered. Traffic police officer prefer that a speed finder, hand-held or mobile, is capable of finding a speeding car within a long range, then the speed finding system must be adapted with a telephoto lens when a photo is needed to clearly identify a license plate of a speeding car for writing a traffic ticket. Accordingly, the entire camera speed finding system adapted with the telephoto lens will become too heavy and is not easily portable. Furthermore, the telephoto lens has a narrow visual angle, so it is too sensitive to handle for mild vibration. Therefore, it is less efficient for the policeman to ban speeding violation.
A conventional bluetooth satellite positioning speed finder is comprised of a satellite positioning module to receive signals from GPS; a radar signal detection module to pick up frequency signal of radar wavelength emitted from a speed finding unit on the road; a data storage unit to store data of coordinates available from a stationery speed finding device; a microprocessor to process GPS signals, the frequency signal of the radar wavelength, and the data of coordinative; a tone broadcasting module to sound alarm according to a command given by the microprocessor; a display module to display status according to a command from the microprocessor; and a bluetooth module to transmit signals from the satellite positioning module and the tone broadcasting module to an electronic device provided with bluetooth function. Accordingly, a warning message is given to a driver of a speeding car to control driving speed to prevent from receiving a traffic ticket.
Other conventional devices take advantage of GPS to duck away from speeding regulation of police. Then a driver of a car adapted with the warning device to speed along without fears. Consequently, it makes even more difficult for the police to ban traffic violation.